The present invention relates to bag package forming apparatus of the type including a mandrel about which a panel of packaging material is formed into a tube, and elements for forming bags and severing each bag from the end of the tube.
One known apparatus of this type is disclosed in Swiss Published Patent Application No. 385,091. Although this device utilizes two panels for producing the bags, it is of course also well known to produce bags from only one panel. However, both types of manufacture incur the same problem, namely the advancement of the tube at or near the just shaped bag.
In the device disclosed in the above-mentioned patent, clamping jaws are displaceably arranged next to a shaping mandrel and as an extension of the jacket face so as to grip the tube at the two edge ribs formed by sealing together the two panels and pull the tube forward. If no such edge ribs exist, provision is made for at least the lowermost edge section of the shaping mandrel to be displaceable. In this arrangement, the clamping jaws press the tube against the shaping mandrel and the entire structure, thus compressed, is moved downwardly. For use of the simpler machinery, the bags must have edge ribs, which entails waste of paper or foil.
Without such edge ribs, the entire hollow mandrel must be moved downwardly. The next bag can thus be sealed transversely only after the entire displacement device has again reached its starting position. This causes a time delay in that it requires an additional process step or, if the sealing jaws were also moved downwardly, a large mass would have to be moved which would also be a drawback for the process sequence.
According to German Gebrauchsmuster [Utility Model Patent] No. 7,536,485, the tube is moved downwardly on oppositely disposed side faces of an endless belt. The drawback here is that this advancement is difficult to synchronize so that the tube may be bent.
German Pat. No. 1,511,636 discloses pulling the bag downwardly by means of the transverse sealing jaws. The countersupport is a sleeve over the shaping mandrel which is moved by means of a rod assembly in grooves of the shaping mandrel together with the sealing jaws. Therefore, the mass that must be moved back and forth is quite considerable.